Specific devices exist for different purposes concerning the testing of a person's attention or ability to concentrate. One such test was proposed by R. M. Pigache for patients suffering from schizophrenia (Perceptual and Motor Skills, 1976, 42, 243-253).
In this particular proposal, the person to be tested listens to strings of digits, letters, words or other sounds, and must react, for example, to particular digits, e.g. the digit "0", by pressing a button with the hand or foot. This test can be carried out so that there is a first phase during which the subject hears the same digits (stimuli) in both ears, then in the next test phase the stimuli are heard in differing order in the different ears, however the subject need only react to certain targets in the two ears (in the following example, this is the "0"), or in a designated ear when information to the other ear serves purely as a distracting signal. The series of stimuli can be delivered to the subject at differing speeds.
At present, however, the tests outlined above can only be carried out at considerable personnel cost. If, for example, nurses or medical technicians read the series of stimuli aloud to the subject, these members of staff must pay very great attention in order both to read out the series of stimuli at a constant speed and very clearly, and to watch very carefully whether the subject is reacting correctly to the targets or is reacting incorrectly where there is no target. The subject carrying our the test must receive appropriate instruction.
The conditions described above can lead to the test results being open to question in that the reproducibility of all tests cannot be guaranteed.